1899.] OSTEOLOGY OF THE TUBI^'ARES. 411 



fossffi, the backward position of the sqiiamoso-parietal wings, the 

 sagittal crest, coronal ridge, and large supraorbital grooves and 

 lachrymals. 



Fig. 2. The skull of Prio)i vittatus, nat. size (p. 389), to show the great de- 

 velopment of the upper jaw, the form of the sujDraorbital grooves, 

 the cerebellar prominence, temporal fossse, and fused lachrymals. 



Fig. 3. Skull of FroceUaria pdagica, nat. size (p. 404), to siiow the feebly- 

 developed supraorbital grooves and the great width of the inter- 

 orbital i-egion of the frontals. 



Fig. 4. The skull of Cymodronia ynelanogaster, nat. size ('p. 404), to show the 

 form of the supraorbital grooves, the spine-like wings of the free end 

 of the squamosal, and the laclirymals, which are partly separated from 

 the frontals by a sj^ace. 



Fig. 5. The skull of an Albatross, Dlomcdea exidans, f nat. size (p. 404), to show 

 the great size of the supraorbital groove and ledge, and the shallow 

 femoral fossa;, confined to the lateral surface of the cranium. 



Fig. 6. The skull of Ocean'Ues ovcanicus, nat. size (p. 404), to show the form of 

 the supraorbital grooves. 



Plate XXIII. 

 Additional Letters. 



a&, = ali3phenoid. m. = meatus iuternus. 



a.o.]). = antorbital process. mes. = mesethmoid. 



ant. =a,ntrum of Highmore. o^. = opi3tbotic. 



an.h.= „ ,, „ jp. = parietal. 



^^;j. = basipterygoid process, ;ja. = palatine. 



ii;.jj. = basitem [Jural platform. ^^ar., ^r. = parasphenoid. 



/>.s. = basi3phenoid. ^jw.a^j. = pneumatic aperture. 



C.6. y. = cerebral vein. 2^?'0. = prootic. 



ew.^. -f-jp;j.ap. = Eustachian groove -f- p^. = pterygoid. 



pneumatic aperture. s.o. — supraoccipital. 



ep.o. = epiotic. s.s. = squamosal spine, 



e.r. = exoccipital. s2- = squamosal. 



/•/• = floccular fossa. t.r. = temporalis recess. 



/a = frontal. ti=: vomer. 



/«.23^. = hemipterygoid. v./' = vagus foramen. 



Fig. 1. Lateral aspect of skull of nestling Oceanodroma leiKorrhoa, outer view, 



X2 (p. 393), to sliow the unclosed sutures. 

 Fig. 2. Lateral inner view, longitudinal section, of same skull (fig. 1), x2, 



to show unclosed sutures. 

 Fig. 3. Dorsal aspect of palatines, pterygoid, and vomer, x2 (p. 39(i), to show 



the form and relations of the hemipterygoid. 

 Fig. 4. Lateral aspect of a portion of fig. 3, X 3, outer view, to show relations 



of hemipterygoid. 

 Fig. 5. Ventral aspect of Felecanoides garnoti, nat. size (p. 383), to show the 



form and great size of the basitemporal platform. 

 Fig. 6. Dorsal aspect of the vomer and neighbouring parts of the skull ol 



Biomedea exulans, | nat. size (p. 390). 

 Fig. 7. Lateral aspect of same dissection as fig. 6, to show form of vomer, 



^ nat. size (p. 391). Note in figs. 6, 7, and 8 the antrum of 



Highmore. 

 Fig. 8. Ventral aspect of skull of Diomedea exulans, to show the schizoguathous 



palate, | nat. size (p. 390). 



